A perfluoropolyether compound has excellent physical properties and is used in wide applications as a lubricant, a water and oil repellent, an antifouling agent, a release agent, or the like. In particular, a perfluoropolyether acyl fluoride is useful itself, and is also useful as an intermediate for the synthesis of various perfluoropolyether compounds. This perfluoropolyether acyl fluoride is known to be able to be prepared by reducing, for example, peroxyperfluoropolyether (that is, the perfluoropolyether compound containing —O—O—).
Conventionally, the reduction of the peroxyperfluoropolyether described above has been performed by contacting with hydrogen gas in the presence of a transition metal catalyst, for example, a transition metal catalyst carried on carbon (for example, Pd/C, etc.). This reduction reaction is shown in the following scheme 1.
wherein Rf is any perfluoro group.
As shown in the above scheme, in the reduction reaction, hydrogen fluoride is generated as a by-product. Since hydrogen fluoride poisons the catalyst, there is a problem that the catalyst activity decreases in the above method.
For the above problem, studies have been performed for maintains the catalyst activity for a long time even in the presence of hydrogen fluoride. As the catalyst, for example, Patent Document 1 discloses a transition metal (Pd, Pt, Rh, etc.) carried on a metal fluoride, and Patent Document 2 discloses a group VIII metal carried on a graphite-like material.
On the other hand, Patent Document 3 discloses that formic acid as a hydrogen donor in the reduction reaction of a carboxylic acid. However, for the reduction of peroxyperfluoropolyether, examples using the hydrogen donor have not been reported.